1. Field of the Invention
The present invention relates generally to automated devices for dispensing single articles from a stacked or grouped array of like articles, and more specifically to a machine which enables a single roofing worker to place and attach stress plates automatically on a roofing structure, to secure insulation and the like. The device automatically picks up a single stress plate from a collection of such plates within the machine, and places it beneath a screw gun extension, whereupon the worker may secure the stress plate with a screw gun attached to the device. When the first plate is secured, the machine automatically picks up the next plate within the machine to repeat the process. Thus, the present machine eliminates need for another worker to locate the plates for the person driving the screw gun.
2. Description of the Related Art
The roofing industry is a labor intensive field, with work often occurring under adverse conditions of hot weather, with hot tar, heavy materials, etc. resulting in considerable strain on roofing workers. Also, considerable "stoop labor" is often involved in the attachment of roofing materials (sheathing, stress plates, insulation, etc.) to a roof structure.
Accordingly, some advances have been made in the field of automated equipment to ease the strain placed upon roofing workers. One such advance was the screw gun extension, described in an earlier issued patent and discussed further below. The device enabled a worker to stand, rather than kneeling or stooping, to position screws and drive the screws to secure roofing materials. However, the materials themselves still required placement by hand, directly upon the roof surface. Subsequently, various automated devices for placing stress plates upon a roof were developed, but each of these machines lacks some critical function provided by the present machine, and/or operates in some different way, than the present machine. A discussion of the related art known to the present inventor, and its differences and distinctions from the present invention, is provided below.
U.S. Pat. No. 3,017,794 issued on Jan. 23, 1962 to Edmond Pouget, titled "Apparatus For Setting Sleeper Screws Or Track Bolts To A Predetermined Degree Of Thickness," describes a device for use in laying or repairing railroad track. The device includes a screw or bolt driving extension, but as the device is intended to secure railroad track to ties or sleepers which are already in place, Pouget does not provide for the automatic laying or placement of any plates or the like, as provided by the present machine. The Pouget device is quite limited in its abilities, as it only provides for the tightening of screws or bolts to a predetermined setting, as limited by feelers and switches in the device. No means is provided for feeding screws through the machine, and driving those screws into plates also fed by the machine, both of which functions are provided by the present invention.
U.S. Pat. No. 4,432,257 issued on Feb. 21, 1984 to Kazuyoshi Yamamoto et al., titled "Shoe Bolt Securing And Removing Apparatus," describes a device for installing and removing bolts securing the shoes or cleats to the underlying track assembly for a tracked vehicle. The device includes means for positioning the bolt driving apparatus precisely over the bolt to be driven or removed, but does not include any means of feeding any article to be secured by the bolt (i. e., the track shoes, cleats, or plates). The present invention includes a generally horizontal magazine adapted to contain a plurality of horizontally stacked stress plates, with the present machine feeding the plates singly to be disposed beneath a screw gun extension comprising a part of the machine.
U.S. Pat. No. 4,510,826 issued on Apr. 16, 1985 to Milton Marks, titled "Extension For A Screwgun," describes a device comprising an elongate telescoping tube having a spring loaded, normally retracted screw gun extension disposed therein. A screw feeder tube extends from the telescoping tube at a shallow angle. Screws are fed singly through the feeder tube, and drop into the lower part of the telescoping tube through a slot therein. The screw gun is then pressed downwardly, to cause the telescoping tube to collapse and lower the extension bit onto the screw, to drive the screw. No additional means is disclosed by Marks for feeding stress plates beneath the lower end of the screw gun extension tube, as provided by the present invention. While the present invention makes use of a screw gun extension similar to the Marks device, it also includes numerous features which extend well beyond the Marks device.
U.S. Pat. No. 4,998,662 issued on Mar. 12, 1991 to Syed R. Hasan et al., titled "Fastener-Driving And Batten-Positioning Machine," describes an apparatus comprising a wheeled base with a screw gun attachment and a generally circular device for the continuous feeding of a continuous length of batten strip. No magazine is disclosed to provide for the single feeding of separate stress plates, as provided by the present invention, nor is any means provided for the separate distribution of single articles, such as stress plates, as provided by the present machine.
U.S. Pat. No. 5,058,464 issued on Oct. 22, 1991 to Hubert T. McGovern et al., titled "Roof Fastener Installation Machine," describes a machine which feeds plates singly from a vertically disposed magazine to a transfer mechanism which places the plates one at a time below a screw gun extension, similar to the Marks device discussed further above. The device operates pneumatically rather than like the present electrically powered invention, and requires an on board source of compressed air, unlike the present machine. A relatively complex pneumatic timing device is required to coordinate the feeding of each plate beneath the screw gun extension, which mechanism is not required with the present machine. The horizontal magazine of the present stress plate feeder overcomes certain problems inherent in vertically disposed magazines, such as the McGovern machine, due to the weight of the plates stacked in a relatively full magazine bearing upon the bottommost plate within the magazine and the resulting difficulty in extracting that plate for use.
U.S. Pat. No. 5,347,707 issued on Sep. 20, 1994 to John R. Beach, titled "Roofing Washer-Dispensing And Fastener-Driving Machine," describes a machine including a generally vertical magazine and single washer or plate dispensing means, and a screw gun, extension, and screw feeder. The device is thus quite similar to that described in the McGovern et al. patent discussed above. The device is purely mechanical, with the exception of the electrically powered screw gun, and washers or plates are advanced singly and horizontally from the bottom of the magazine by a horizontal slider mechanism. They are captured beneath the screw gun by a spring loaded latch mechanism, to position them for securing with the screw gun. The present machine utilizes a horizontally disposed magazine, with plates being disposed with their planar surfaces generally vertical therein and advanced singly by an electric motor controlled by a microswitch, unlike the Beach machine.
Finally, Soviet Patent Publication No. 856,896 published on Aug. 25, 1981 illustrates a nail or fastener feeding device which transfers fasteners from one storage area to another. No means is shown for securing the fasteners to another article, nor are any other articles (e. g., stress plates or washers, etc.), or means of distributing or placing them, shown in the drawing figures of the '896 Soviet publication.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.